Junk mail is a fact of life. We don't like it and it costs us a lot of money to deal with, but it's only getting worse.
You should strive to go through your junk mail folder at least every-other day. If you let it go longer than that, there could be so many messages in your junk mail folder that you won't be able to properly review them.
After taking the time to review the junk mail and train the filter, you should empty the junk mail folder. This is easy to do. Right-click on the "Junk e-mail" folder in the folder tree and select "Empty Junk e-mail folder".
Click "Yes" to confirm that you want to empty the folder.
Your Junk e-mail folder is now empty and ready for the next round of junk mail.